217989797717 has 4 divisors (see below), whose sum is σ = 218055599340. Its totient is φ = 217923996096.

The previous prime is 217989797699. The next prime is 217989797719. The reversal of 217989797717 is 717797989712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 87167248081 + 130822549636 = 295241^2 + 361694^2 .

It is a cyclic number.

It is not a de Polignac number, because 217989797717 - 2¹⁰ = 217989796693 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217989797719) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 32895842 + ... + 32902467.

It is an arithmetic number, because the mean of its divisors is an integer number (54513899835).

Almost surely, 2^217989797717 is an apocalyptic number.

It is an amenable number.

217989797717 is a deficient number, since it is larger than the sum of its proper divisors (65801623).

217989797717 is an equidigital number, since it uses as much as digits as its factorization.

217989797717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65801622.

The product of its digits is 196036848, while the sum is 74.

The spelling of 217989797717 in words is "two hundred seventeen billion, nine hundred eighty-nine million, seven hundred ninety-seven thousand, seven hundred seventeen".